Electric power lines, mammal bodies, vehicle engines, and aircraft are examples of the many living organisms and objects that produce and retain heat. These objects and bodies are visible in the infrared wavelengths of light compared to objects in the background because hot bodies strongly radiate infrared waves. The objects in the background are those relatively cooler objects surrounding the hot body.
Missile guidance systems track and follow a target using an infrared seeker to locate the infrared emissions from the target. The infrared seeker, also referred to as a heat seeker, includes infrared temperature sensors and is calibrated to identify temperature of an object from the color of the object in an infrared photograph.
For space based system, a cryogenic vacuum chamber simulates space conditions. Cryogenic blackbody cores are used to characterize or calibrate infrared seekers. Teaching, characterizing, and calibrating an infrared seeker to record what specific color represents a specific temperature involves several steps. A cryogenic blackbody core is heated. Then a temperature sensor reads the temperature of the heated blackbody core. An infrared camera takes a photograph of the heated blackbody core and displays colors according to the temperature of the blackbody. The infrared seeker memory is programmed to store a color-temperature association between the measured temperature and the color of the object on the infrared photograph. The infrared seeker is programmed to know that the color displayed by the blackbody core corresponds to the temperature read by the temperature sensor.